Mold Less Casting, a New Method for Droplet Based Part Manufacturing



In the new method of rapid manufacturing, the molten metal is dropped on a substrate, making layers after another. This method has the potentiality to be used for complicated castings which are difficult to make their molds and patterns as usual ways. In droplet-based manufacturing process the castings are constructed by molten metal droplets having proper flow rate, temperature and diameter. In this paper a new system is designed and constructed which makes 3D parts and patterns by depositing molten metal droplets. Raw material wire melts and droplets are generated in droplet generating head. Molten metal Droplets deposit on a high temperature bed making the first layer. Next layers place on the previous ones to shape the final arbitrary part. These droplets are surrounded by natural air. Here tin60%, lead40% alloy wire is used. it is possible to apply other materials or wires having different diameters just with a little change in system. The wire is fed in special speeds which lead to different rates of droplets leaving the nozzle. Droplets have three properties which affect the layers and depositing way. These properties are droplet temperature and volume and their deposition rate. To control them several parameters of the system must be adjusted appropriately. At first it is assumed that these machine parameters are outlet nozzle diameter and feeding wire speed and also droplet temperature which affect droplet volume and deposition rate. Droplet temperature is measured exactly where they leave outlet nozzle. Droplet volume is estimated by several experiments, which lead to learn how different machine parameters create various droplet volumes. By knowing droplet volume and feeding wire speed, droplet rate can be calculated.In this paper the design essence of the constructed droplet based manufacturing machine is told. And dependency of droplet properties to machine adjustments is studied. These studies are done to control droplet properties. By knowing droplet properties, the moving speed of CNC heating table is determined.